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Old 01-10-2010, 02:31 PM   #1 (permalink)
Master EcoModder
Join Date: Nov 2009
Location: Leadville, CO
Posts: 509

Maroon Ballon - '98 Chrysler Town & Country LXI
90 day: 26.42 mpg (US)

MaEsTRO - '95 Geo Metro 5spd hatch, 3 cyl
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VOM as instrumentation??

This is a question for people who are knowledgeable about DC electronics and EVs.

I just installed a hub motor on my bike, and the throttle has a 3 LED meter that is supposed to gauge battery level, but so far, as long as the power is on, all 3 lights are lit. The way it's supposed to work is that the green shows full charge, the yellow means the battery is getting weak, and the red indicates empty. They're not all supposed to be lit at the same time. The motor and controller came as a kit, and the battery was a separate purchase, but everything is 36V. I'm wondering if the problem has something to do with the fact that I'm running a 36V 20AH lifepo4 instead of lead-acid.

I would eventually like to get a Cycleanalyst, but it's not in the budget for a while. In the meantime, Harborfreight is going to be putting their cheap volt-ohm meters on sale next weekend for $1.99. That I can afford!

My question is; how can I rig up a VOM as a dedicated "fuel gauge" to monitor the state of my battery, as opposed to idiot LED lights that don't function properly anyway? Would I want to monitor voltage or amperage, or could I get 2 VOMs and monitor both?

Thanks in advance for your shared genius.

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